Automatic storage and retrieval system



United States Patent R M c m 3,076,566 2/1963 Dennis 214/164 [72] Inventors kg c kledge, Fla., and 3,297,379 1/1967 Artaud et ai.... 312/223 Barney 0. Rae, Shorewood, Wisconsin 3,402,836 9/1968 Debrey et a1. 214/164 [21] Appl- 670,094 Primary Examiner-Gerald M. Forlenza [22] Filed Sept. 25, 1967 Assistant Examiner-Raymond B. Johnson Patented 1970 Attorney-Hugh R. Rather [73] Assignee Cutler-Hammer, Inc.

Milwaukee, Wisconsin a corporation of Delaware Division of 1965 ABSTRACT: An automatic warehouse system which allows now an operator to sit at a fixed station and by placing punched cards into card readers and pressing a 60" button can cause a fork to take one article from a pickup station into storage [541 g gg gf STORAGE AND RETRIEVAL and to retrieve any other article from storage on its return trip 11 Cl 20 Draw Fi s and bring it to a selected setdown station and then return to Inns 8 8 the starting point. Depending upon the information punched [52] U.S.Cl 2l4/l6.4 on the card it can skip either the storage or the retrieval [51] lnt.Cl. B65g1/00 operation and perform the other or it can cause the fork to oi'Search move an article from any rack in the warehouse to any other 1642;212/(lnqmred) rack without returning to the pickup or setdown stations. in performing these movements in three dimensions, the system Refuences is provided with apparatus which recalculates the position of UNITED STATE AT the fork every step of the way so as to eliminate any error that 2,988,237 6/1961 Devol 214/16.4X may occur.

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Patented Nov. 3, 1950 3,537,602

Sheet 3 of 17 Patented Nov. 3, 1970 3,537,602

Sheet or 1? STORE CAR 0 READER NOJ P21 P22 PR3 PR4 P26 P27 R8 PM 6A7? A99A1o Patented Nov. 3, 1970 3,537,602

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Sheet 3 or 17 BINA $UBTRACTOR FOR BQIDGE MOVEMENT NMA TES

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HOUT MOVEMENT Patented Nov. 3, 1970 3,537,602

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BEDGE MOTOIZ CONTEOL TQOLLEY MOTOR Patented Nov. 3, 1970 4 3 6 8 H B c c c c c c c c c c c S s s S S s S S S s L L L Q a i mi L L wt M L Mi mm Mi Riv Patented Nov. 3, 1970 v 3 5'*7 602 Sheet o: 17

2 ND STAG E 520. TAGE ALE FOR- REV.

Patented Nov. 3, 1970 Sheet L of 17 IIII PROGRAM I I CARD I BRIDGE 4 (HOME) TROLLEY- 34 (HOME) HOIST X9 (ROTATE) ROTATE X3 (NORTH) HOIST TO ROTATE POSITION 8| ROTATE BRIDGE 8 HOIST TO STORE POSITION II- PROGRAM 4 Iv CARD l BRIDGE SAME AS PR3 TROLLEY- SAME AS PR2 BCTD HOIST SAME AS PR3 ROTATE SAME AS PRI MOVE TROLLEY INTO BIN {III- IB- PROGRAM 5 I CARD I BRIDGE SAME AS PR3 TROLLEY- SAME AS PR2 AGTD HOIST XG(IPOS.BELOW PR3) ROTATE SAME AS PRI LOWER HOIST 8 BACK INTO AISLE II- PROGRAM 5A I CARD I BRIDGE SAME AS PR3 TROLLEY- SAME AS PRZECTD HOIST SAME AS PR3 ROTATE- SAME AS PRI (BIN FULL) BACK INTO AISLE II PROGRAM 6 I CARD I BRIDGE SAME AS PR3 TROLLEY SAME AS PR2 HOIST-- SAME AS PR5 ROTATE SAME AS PRI ND MOTION I} PROGRAM 6A I CARD I BRIDGE X4 (HOME) TROLLEY- SAME AS PR2 HOIST X9 (ROTATE) ROTATE SAME AS PRI BRIDGE TO HOME 8 HOIST TO ROTATE POSITION STORE CYCLE PROGRAM 7 CARD I BRIDGE- SAME AS PR3 TROLLEY- SAME AS PR2 HOIST SAME AS PR5 ROTATE SAME AS PRI no mono" PROGRAM 7A I CARD I BRIDGE- 4 (HOME) TROLLEY X34 (HOME) HOIST 9 (ROTATE) ROTATE-- SAME AS PRI TROLLEY TO HOME PROGRAM 8 I CARD I BRIDGE SAME AS PR3 TROLLEY- SAME AS PR2 HOIST SAME AS PR5 ROTATE SAME AS PRI NO MOTION PROGRAM 8A cARo I BRIDGE 4 (HOME) TROLLEY 34(HOME) HOIST S (ROTATE) ROTATE- XZIMIDDLE) ROTATE TO CENTER PROGRAM 9 I CARD I BRIDGE SAME AS PR3 TROLLEY- SAME AS PR2 HOIST SAME AS PR5 ROTATE SAME AS PRI NO MOTION PROGRAM 9AI CARD I BRIDGE 4 (HOME) TROLLEY-- 34 (HOME) HOIST XS (PICK-UP) ROTATE 2 (MIDDLE) SET LOAD DOWN 5 CLEAR SYSTEM CHECK AISLE 8 ROTATE AUTOMATIC STORAGE AND RETRTEVAL SYSTEM CROSS REFERENCES TO RELATED APPLICATION This application is a division of our copending application Ser. No. 498,326, filed Oct. 20, 1965 now 11.8. Pat. No. 3,504,245.

BACKGROUND OF INVENTION This invention relates to automatic storage and retrieval systems and more particularly to an electrical system for controlling multiple coordinate movements in three dimensions of a crane or the like to place articles in storage racks or bins ofa warehouse and to remove articles therefrom under the control of punched cards or the like information bearing media.

While not limited thereto, the invention is especially applicable to control ofthe left or right and forward or back trolicy and bridge movements, respectively. and the vertical and rotary hoist and fork movements, respectively, of a stacker crane.

Cranes of this type have heretofore been operated under manual control and under partial automatic control. Under manual control, the operator rides the fork so that he can see where it is going and from individual hand levers first runs the trolley in a cross aisle along the bridge to a point opposite the desired long aisle and rotates the fork, which may carry a twenty foot long bundle of metal bar stock, so that the load will fit into the long aisle. The operator then operates additional hand levers to run the bridge whereby to move the load down the aisle and to run the hoist to raise the load adjacent the desired rack. The operator then operates the trolley and hoist levers again to move the load over the rack, to lower the load onto the rack and to reverse the trolley back into the aisle. Under partial automatic control, a keyboard, dial or the like has been used to insert directive information into a control system which then controls the movements of the loadcarrying fork. But these partial automatic control systems have been constructed and arranged on a counting basis so that after each operation, storing or retrieving as the case may be, the fork must return to the starting point before it can be sent out again on another errand. In these known systems, the directive information was put in initially and correct operation depended on its remaining sequentially accurate as stepping switches or the like were used. Thus, any error that might get in would give the device a false lead.

SUMMARY OF THE INVENTION This invention relates to an automation system which allows the operator to sit at a fixed station and by merely'placing punched cards (or equivalent information bearing media) into card readers or the like and pressing a GO button can cause the fork to take one article from the pickup station into storage and to retrieve any other article from storage and bring it to a selected setdown station before returning to the starting point or it can skip either the storage or retrieval operation. Or, depending upon the information punched on the cards, the system can cause the fork to move an article from any rack in the warehouse to any other rack without returning to the pickup or setdown stations. The invention has been devised to do this with the utmost reliability as will hereinafter appear.

An object of the invention is to provide an improved automation system for multiple coordinate motions control having greater reliability.

A more specific object of the invention is to provide an improved threedimensional motions control system which is continuously self-checking to avoid error.

Another specific object of the invention is to provide a motions control system of the aforesaid type which is constructed to provide better accuracy.

Another specific object of the invention is to provide a motions control system of the aforesaid type which recalculates its position every step of the way so that the system eliminates errors and always knows where it is.

Another specific object of the invention is to provide a motions control system of the aforesaid type which does the job faster because it can perform a second operation without coming to the home or starting point after the previous operation.

Another specific object of the invention is to provide a motions control system of the aforesaid type employing fully digital control which is especially adapted for sensing the direction in which it must move, for sensing how far away it is from its destination and for sensing slowdown points.

Another specific object of the invention is to provide an improved multiple coordinate, threedimensional control system for a stacker crane having optimum flexibility in that it is capable of performing a large number of functions.

A further specific object of the invention is to provide an improved numerical, direct static logic system for controlling interlocked movements of a multiple coordinate motions stacker crane from punched cards or similar digital code hearing media.

Other objects and advantages of the invention will hereinafter appear.

According to the invention, there is provided a direct static logic system for controlling a stacker crane, direct" meaning that a positive input to a logic element produces a positive output and a zero input produces a zero output and no signal inversion takes place in any of the logic elements except the NOT logic element which purposely inverts the voltage.

The heart of the system is a digital computer of the binary code subtracting type which computes the directions and the distances every step of the way and the slowdown points at the proper times rather than relying on a less reliable sequencing scheme. This computer subtracts the desired-position indicative binary code from the actual-position indicative binary code for each of the bridge, the trolley and hoist and provides both a direction indicative signal at one of two possible outputs and a distance indicative difference binary code for controlling the respective motions. These subtractions are performed at predetermined steps along the way when the actualposition indicative binary codes are read so that any error which might have occurred at one point is completely eliminated when a new reading is taken and a new subtraction made. The desired-position indicative binary codes are obtained from punched cards by card readers and applied directly to the subtractor. Two card readers are used, one for storage codes and the other for retrieval codes to allow the crane to go from any place to any other place. The actualposition indicative binary codes are read from sets of magnetic code bars by proximity readers moving with the bridge, trolley and hoist, respectively, these sets of code bars being mounted along their respective paths of travel. Although difference binary codes of large magnitude are obtainable, since seven, six and six bit binary codes are used for the bridge, trolleyand hoist, respectively, all codes larger than slowdown values function in the same way in conjunction with the direction indicative signal to cause continuous base speed operation whereas small difference binary codes such as equivalent decimal values of 3, 2 and l for the bridge and 2 and l for each of the trolley and hoist initiate slowdown action preparatory to stopping at zero difference, it being recognized that these small difference binary codes indicate that the moving device, as the case may be, is approaching its desired destination.

Rotary motion of the mast which mounts the article-supporting fork does not require computer control in the illustrated embodiment since its movements for warehousing application are relatively simple. That is. the fork has only three positions, a middle or westwardly directed position for loading and unloading purposes and north and south positions for the racks on opposite sides of the long aisle. The rotary position indicative codes, which are one hole codes for north or south or middle, are obtained from the punched cards by the card readers and are applied directly to the rotate motor control, the rotation being stopped at the proper position by limit switches.

' The system is also provided with means for performing auxiliary functions including bypassing the storing or retrieving cycle under the control of a bypass card but allowing the other unbypassed cycle to take place; detecting a full rack or bin and returning the load to the pickup station; at the end of a storing cycle when the empty fork is in the long aisle adjacent the just-filled storage rack, determining whether the article to be retrieved is in a new aisle or side and if so, selecting another binary code program from the punched card which will cause movement of the bridge first to 'a cross aisle to allow shifting of the trolley or rotation of the fork; in conjunction with the above new aisle or side determination, selecting the nearest cross aisle for trolley shifting or fork rotation by choosing between two alternatives in the selected other binary code program, one of which will route the bridge back to the west (home) cross aisle when the just-filled storage bin is within a first range of bridge positions and the other of which will route the bridge to the middle cross aisle when the just-filled storage bin is beyond said range in theremaining bridge positions, it being assumed, of course, that these ranges of bridge positions are nearest the respective cross aisles; and selecting under manual control either one'of two setdown stations to which the retrieved article is to be brought by selecting one of two retrieval programs from the punched card. Means for performing other particular auxiliary functions such as interlocks, lockouts, restrictions on certain movements, preset conditions, etc., will becomeapparent as the description proceeds.

Y BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantages of the invention and the manner of obtaining them will best be understood by reference to the following description of an embodiment of an automatic storage and retrieval system taken in conjunction with the accompanying drawings, wherein:

FIG. I is a perspective end view of a warehouse schematically showing three bays of racks or bins and the stacker crane installed therein;

FIG. 2 is a top plan view of an exemplary warehouse schematically showing a multiplicity of rows of racks or bins separated by eight long aisles and two cross aisles and a stacker crane resting in the west end cross aisle;

FIGS. 3 through 14 are circuit diagrams schematically showing the automatic storage and retrieval system;

FIGS. I and 16 are circuit diagrams showing details ofa binary code subtractor shown as a rectangle in the system of FIGS. 3--14;

FIG. 17 on sheet 14 shows details of a signal converter used in FIG.

FIGS. 18 and 19 diagrammatically, show the sequential operational program steps for the storage and retrieval cycles, respectively, of the systems of FIGS. 1-16, including selectable alternate program steps; and

FIG. 20 on sheet 6 is a block diagram showing how the circuits of FIGS. 3 14 are assembled.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the warehouse shown therein comprises a pair of side tracks or bridge rails l and 2,.one along each side of the warehouse near thetop, on which a stacker crane 3 is supported and along which it rolls the length of the warehouse. The bays 4 of racks or bins in which articles are stored stand on the floor of the warehouse. As shown schematically in FIG. I, each bay 4 comprises a center frame 5 and horizontal rows and vertical columns of bins 6 supported on opposite sides of the center frame so that they are accessible from the long aisles 7 which run between the bays. Altematively, racks may be used instead of bins which would consist of spaced apart steel beams in rows and columns projecting in cantilever fashion in opposite directions from main frame 5. As will be apparent, such racks could support elongated articles such as metal bar stock including angle irons, rods, etc., in groups of bundles which would span two or more of the steel beams. While only three enlarged bays of storage bins are shown in FIG. I for clarity of illustration it will be apparent that a larger number thereof is normally used in a warehouse as shown in the top view of FIG. 2.

As shown in FIG. I, stacker crane 3 comprises a bridge 8 spanning the warehouse and supported at its opposite'ends on side rails l and 2. The ends of the bridge are provided with wheels (not shown) driven by an electric motor drive in known manner to afford running of the bridge the length of the warehouse.

The stacker crane also comprises a trolley 9 which is provided with wheels (not shown) driven by an electric motor drive in known mannerto afford running of the trolley the length of the bridge across the warehouse. For this purpose, the bridge is provided with suitable rails (not shown) for the trolley to roll along. The trolley is additionally provided with a suitable ring gear structure or the like (not shown) and a rotate motor drive for rotating a mast 10 suspended therefrom.

The stacker crane further comprises a hoist 11 for moving a fork F or other article supporting device up and down along mast 10 so as to position the article opposite any bin in a column thereof. Magnetic code bars 12 are mounted in predetermined spaced apart relation upwardly along mast l0 and have binary codes starting with 3 at the lower end to be read by a hoist proximity reader (hereinafter described and shown in FIG. 5) to control the positioning of the fork relative to the bins or racks in which articles are to be stored, binary codes 2 and 1 being used for slowdown of the hoist.

A warehouse having a multiplicity of rack bays 4 is shown in FIG. 2, these bays beingseparated by long aisles 7 and a home or west cross aisle and a center cross aisle, shown in top plan view. In the example of warehouse shown in FIG. 2, there are eight long aisles providing seven full bays with their bins backto-back and two half bays, there being one such half bay facing each of the first and eighth long aisle with its back against the side wall of the warehouse.

The home cross aisle at the west end of the warehouse is provided for loading and unloading articles onto and from the fork. For this purpose, there are provided an entry conveyor EC leading eastwardly to a pickup station in the home cross aisle and a pair of exit conveyors XCl and XCZ leading westwardly away from respective setdown. stations Nos. 1 and 2 in the home cross aisle. For exemplary purposes, the pickup sta tion has been located at the trolley binary code position hav' ing a decimal equivalent of 34 (hereinafter called binary code position 34) and the setdown stations Nos. 1 and 2 have been located at trolley binary code positions 9 and 19, respectively, the trolley positions having binary codes starting with 3 at the south end of the bridge to the north end thereof. The entry conveyor is arranged to move an article directly onto the fork when the latter is positioned slightly below the top of the entry conveyor at hoist binary position 6. In a similar manner, each exit conveyor is arranged to move an article directly off the fork after the latter deposits an article thereon in response to lowering of the hoist to binary code position 6.

The trolley and bridge are also provided with positioning control devices. As shown schematically in FIG. 2, magnetic code bars 13 are mounted in predetermined spaced apart relation along the bridge and have binary codes starting with 3 at the south end to beread by a trolley proximity reader hereinafter described and shown in FIG. 6, binary codes 2 and 1 being used for slowdown. Also, magnetic code bars 14 shown in FIG. 2 are mounted along one bridge track 2 along the path of travel of the bridge and have binary codes starting with 4 at the west aisle to be read by a bridge proximity reader hereinafter described and shown in FIG. 6, binary code 3, 2 and 1 being used for slowdown. Magnetic code bars 13 and 14 and their associated proximity readers afford control of the positioning of the trolley and bridge, respectively.

The manner in which the system shown in FIGS. 3 to 14 is constructed and the logic and other elements connected to one another will become apparent from the following descrip- 

